The present invention relates to an electronic apparatus that performs heat dissipation treatment using a circulating cooling liquid.
An electronic apparatus, such as a desktop type computer, a notebook type computer, and a mobile communication device, is provided with a microprocessor (MPU). In recent years, with an improvement in processing speed of the microprocessor, and enhancement features and advanced performances of the microprocessor, there is an increasing tendency in heating value during operation. In order for the microprocessor to maintain stable operation, generated heat must be quickly discharged to the outside to thereby increase heat dissipation efficiency.
For that reason, an electronic apparatus provided with an air-cooled cooling device for cooling the microprocessor is generally used. This cooling device includes a heat sink that takes and dissipates heat of the microprocessor, and a cooling fan that sends a cooling airflow to this heat sink. Since the heating value of the microprocessor has possibly been increased continuously as mentioned above, a countermeasure for solving the problem has been required.
In the air-cooled cooling device, in order to improve a cooling capability, countermeasures, such as large-sizing of the heat sink, a performance improvement of the cooling fan, or the like are taken. However, when using a large-sized heat sink, there may arise a problem that a large-sized electronic apparatus is also required in order for the heat sink to be incorporated therein. Meanwhile, in order to achieve a performance improvement of the cooling fan, large-sizing of a fan structure, an increase in a rotational frequency of the cooling fan, or the like is required, but there may arise a problem that this technique cannot prevent the electronic apparatus from being large-sized or a fan noise from being increased. Particularly, in a notebook type computer, in addition to the cooling capability, portability, that is, the size and weight of the apparatus will become an important factor, and silence, that is to say, the apparatus works quietly during operation will also be an essential factor, but the countermeasures for improving the cooling capability described above are contradictory to those.
Therefore, there has been proposed a cooling system of liquid-cooling type that utilizes as a coolant a liquid, such as water having a specific heat far higher than that of air (for example, refer to Japanese Patent Application Laid-Open No. 2004-95891 and Japanese Patent Application Laid-Open No. 2004-111829). According to the cooling system, a heat reception portion is provided near a microprocessor housed in a housing, a heat dissipation portion is housed in a display unit, a circulation path which circulates a liquid coolant between the heat reception portion and the heat dissipation portion is provided, and heat of the microprocessor having transmitted to the heat reception portion is transported to the heat dissipation portion via the coolant which flows through the circulation path.
Moreover, various kinds of electronic apparatuses which are devised to increase the heat dissipation efficiency have been proposed (for example, refer to Japanese Patent Application Laid-Open No. 2002-16200 and Japanese Patent Application Laid-Open No. 11-354951 (1999)). In the Japanese Patent Application Laid-Open No. 2002-16200, there is described an electronic apparatus configured so that a fin of a heat dissipation member which is thermally coupled to electronic parts housed in an apparatus housing may be increased or reduced in conjunction with an open/close operation of a cover body. In the Japanese Patent Application Laid-Open No. 11-354951, a portable electronic apparatus configured so that the heat dissipation portion may freely protrude from the housing is disclosed.
As for the notebook type computer, not only enhancement featured and advanced performances of the microprocessor, but also miniaturization and portability are also highly required. Efficient heat dissipation treatment in limited room is therefore desired for a possible increase of the heating value.